A magnitude-6.8 earthquake hit off Japan's southern coast Monday, prompting the Meteorological Agency to issue a tsunami warning.

The quake struck off the coast of Ishigaki island, near Japan's southern island of Okinawa, around 1,000 miles (1,600 kilometers) south of Tokyo. It struck at a depth of about six miles (10 kilometers), the agency said.

Naoto Ohtake, a police official on Ishigaki, said there were no immediate reports of damage or casualties on the island, a popular resort destination with a population of 40,000.

"Nothing fell off during the quake. Electricity, water and gas are all working," Ohtake said.

Japan is one of the world's most earthquake-prone countries. The most recent major quake in Japan killed more than 6,400 people in the western port city of Kobe in January 1995.